This invention relates to a new method for inserting heterologous genes into the genome of a bacteria using a combined plasmid. The combined plasmid provides a cis complementation of transposase genes and transposable elements. The method involves the homologous recombination of a carrier plasmid and a functions plasmid to form the combined plasmid. The carrier plasmid contains a transposable element which flanks a generic expression cassette. The functions plasmid comprises transposase genes which complement the transposable element on the carrier plasmid. The combined plasmid is then transferred to a recipient and the recipient is monitored for integration of the generic expression cassette into the genome. The combined plasmid is preferably created by an in vivo homologous recombination of the carrier and functions plasmids.